The present invention relates to a vinyl group-containing diarylethene monomer expressed by formula (1) and a polymer thereof having optical properties. More particularly, it relates to a vinyl group-containing diarylethene monomer of formula (1), suitable for controlled polymerization and a polymer thereof having excellent optical properties such as control characteristics of optical signal, photochromic characteristics, and control characteristics of optical reflectivity by introducing the diarylethene monomer of formula (1) into the polymer chain, 
wherein Z1 and Z2 are independently cyano group or attached form of 4-6-membered ring optionally substituted with one or more fluoro atoms; and
Ar1 and Ar2 are independently 
where X and Y are 0, S, NH or Nxe2x80x94CH3; R2 and R5 are optionally substituted C1-C3 alkyl; R3 is H, F or optionally substituted C1-C3 alkyl; and R4 and R6 are independently H, CH3, C(xe2x95x90O)CH3, isoxazole, vinyl, C(xe2x95x90O)xe2x80x94Ar3xe2x80x94CHxe2x95x90CH2, C(=O)-Ar4, or N(Ar5)2, where R4 or R6 of either Ar1 and Ar2 should be vinyl or C(xe2x95x90O)xe2x80x94Ar3xe2x80x94CHxe2x95x90CH2 and Ar3, Ar4 or Ar5 should be optionally substituted benzene or thiophene.
Demand in photochromic lenses, high density photochromic recordings, high speed optical communications, and large scale integrated circuits has been dramatically increased with development of technologies in shielding of sun light, optical signal processing, optical transfer, optical filter and the like. The optical devices contain photochromic and photorefractive materials which change color and transparency with light irradiation and are capable of signal recording and/or reproducing with laser irradiation. Among organic photochromic materials, diarylethene compounds have excellent thermal stability and repetitive durability, thus leading to proposals for their use in optical applications such as optical devices, optical recordings and the like.
It has been reported that diarylethene compounds have high thermal stability and photochromism so that they are useful for functioning in a polymer film [Refractive index changes in photochromic diarylethene derivatives in polymethylmethacrylate films, Journal of Photochemistry and Photobiology A: Chemistry, Volume 95, Issue 3, May 10, 1996, Pages 265-270, Takashi Yoshida, Koichi Arishima, Fumihiro Ebisawa, Mitsutoshi Hoshino, Ken Sukegawa, Atsushi Ishikawa, Tatsuya Kobayashi, Makoto Hanazawa and Yukio Horikawa]. However, when the diarylethene compounds are used for preparing polymer films, it is difficult to obtain homogeneous thin film due to insufficient compatibility of diarylethene compounds with polymer resin and sufficient photochromic effect due to the agglomeration among photochromic materials. In addition, when a large amount of diarylethene compound is used to enhance the efficiency, the obtained film is not clear and phase separation may occur with storing for a long period time because the diarylethene compound is dissolved out or forms microcrystals. Therefore, it is unreliable and lack of storage stability for long term use.
In order to be free of these defects, Japan Patent Publication No. 6-240242 discloses polymeric photochromic composition comprising a polymer having methacryl-base diarylethene groups bonded to a polymer chain. However, the methacryl-base diarylethene compounds have low reactivity during the polymerization and do not bond efficiently to the polymer chain because it is difficult to control the blocks, thus being inappropriate in the preparation of the polymer having hyper-branches.
Accordingly, the necessity of developing monomers having high reactivity and polymers using thereof is keenly demanded.
Accordingly, an object of the present invention is to provide a diarylethene monomer of formula (1) capable for the preparation of a polymer having excellent optical properties through anionic polymerization, cationic polymerization or radical polymerization.
Another object of the present invention is to provide a polymer having excellent optical properties such as control characteristics of optical signal, photochromic characteristics, and control characteristics of optical refractivity as well as transparence without phase separation.
Further object of the present invention is to provide a composition comprising 0.01-99.8 weight % of a diarylethene monomer of formula (1), 0-99.8 weight % of a comonomer, and 0.19-5 weight % of a polymerization initiator, thus capable for thin layer-coating on the various structure of substrates.